Hydraulic pumps



`Ian. 26, 1960 J. H, PAHL .HYDRAULIC PUMPS Filed Jan. 29,` 1958 6Sheets-Sheet 1 IN V EN TOR. JFIMEJ l1. PAHL s IN. @Hrm AT1-onus Ys Jan.26, 1960 J. H. PAHL 2,922,373

HYDRAULIC PUMPS Filed Jan. 29, 1958 6 Sheets-Sheet 2 SUCTION STROKE ,ALLRANGE:

INV ENTOR. JAM/5J l1. PAHL Ff@ 4 1 @@mfw ATT-oR/vs-YJ Jan. 26, 1960 J.H. PAHL HYDRAULIC PUMPS 6 Shoots-Sheet 3 Filed Jan. 29, 1958 6 EN ww SQN mv INVENTOR. 4N/EJ H. PAH/ TToANEY-J INVENTOR.

6 Sheets-Sheet 4 .ih/ws: H. PAHL.

J. H. PAHL HYDRAULIC PUMPS Jan. 26, 1960 Filed Jan. 29, 1958MEaPREssz/RE MEoJJ/F/.ow

14 TToR/v YJ Jan. 26, 41960 J. H. PAHL 2,922,373

HYDRAULIC PUMPS Filed Jan. 29, 1958 6 Sheets-Sheet 5 ,4 T Tak/ve Y6 Jan.26, 1960 J. H. PAHL 2,922,373

HYDRAULIC PUMPS Filed Jan. 29, 1958 6 Sheets-Sheet 6 ll/GH PRESSURE LowVoz.. FLow JA//Es h'. PA H1..

FIEL JJ www 6M A -r-roRNE Y6 HYDRAULIC PUMPS James H. Pahl, Excelsior,Minn., assignor to Rodgers Hydraulic, Inc., Minneapolis, Minn., acorporation of Minnesota Application January 29, 1958, Serial No.712,020 11 Claims. (Cl. 103--37) This invention relates to new anduseful improvements in hydraulic pumps, and more particularly to pumpscapable of operating at a plurality of different effective pressures byselectively varying the volumetric flow of, the pressure fluid throughthe pump, and whereby the effective pressure 'of the fluid at the pointof Vuse may be progressively varied in accordance with that required toaccomplish the work at hand.

An object of the present invention is to provide a compact, light weightpump of very high capacity and efciency, which may readily be manuallyoperated by the manipulation of a single operating lever to deliver thedesired pressure with minimum elfort, said pump also having a singlecontrol lever for controlling the volumetric flow of the pressure fluidthrough the pump to selectively vary the effective pressure thereof, andwhereby the pump may be operated at a given speed with a minimumrequired lever reaction force, and as the load demand increases, thepump may readily be adjusted to deliver a greater lifting force relativeto the volume of iluid ilow without any substantial increase in thelever reaction force.

A further object of the invention resides in the novel construction ofthe means for relatively adjusting the operation of the valves whichcontrol the volumetric iiow of the pressure fluid to vary the workingpressure of the pump.

A further and more specific object of the invention resides 'in theconstruction of the cam means provided for varying the volumetric flowof the iluid within the pump, such means comprising a plurality of camelements each representing a dierent effective fluid pressure and havinga control handle conveniently located on the pump housing, whereby theoperator may readily and quickly shift said handle from one position toanother to vary the volumetric ow and pressure of .the fluid deliveredby the pump, in accordance with that required by the particular job tobe done.

Other objects of the invention reside in the concentric and nestedarrangement of the pistons and cylinders of the various pump meanswithin a common cylinderforming member, thereby to provide a morecompact unit; in the manner in which said parts are slidably interiittedwith one another within said member; in the unique arrangement of all ofthe various fluid control valves and tluid circulating passages in asingle valve block having means for detachably securing it to thecylinder housing, and whereby all of the valve elements and theircomplemental spring elements, including the valve unseating means orvalve litters, may be completely assembled in said valve block beforesecuring the valve block to the cylinder housing; and in the specilicconstruction of the valve-unseating mechanism, including the laterallyspaced valve lifter elements and the cross head in which they Y*2,922,373 1C@ Patented Jan.25,y 1 960 are adjustably mounted, and theoperative connection between the cross head and the iuid pressurecontrol handle conveniently located on the pump housing.

These and other objects of the invention and the means for theirattainment will be more 'apparent from the following description takenin connection with the -accompanying drawings. A

In the accompanying drawings there has been disclosed a structuredesigned to carry out the various objects of the invention, but it is tobe understood that the invention is not confined to the exact featuresshown, as various changes may be made within the scope of the claimswhich follow.

In the drawings: Figure 1 is a side elevational view of the pump withthe wall of the housing partially broken away to show the pump means,the pressure relief valve, and the valve unseating means located withinthe pump housing, and

also showingl the fluid reservoir in the lower kportion of the housing;Y'

Figure 2 is a rear View of the pump partially broken away as in Figurel, and indicating the three positions of the pump control handle, someof the parts being cu-t away;

Figure 3 is a miniaturetop'viewof Figure 1, with the operating lever andcontrol handlev removed;

Figure 4 is an enlarged vertical sectional View on the line 4-4 ofFigure l, indicating 'thedirectional flow of the pressure Huid throughthe pump during the suction stroke, and when the control handle ispositioned Vfor low pressure operation;

Figure 5 is a horizontal sectional view on the line 5 5 of Figure 1l,wherein the arrows indicate the directional flow of the pressure fluidin the valve block during the pressure stroke yand the two controlvalves are open, as when the control handle is positioned for highpressure low volume operation;

Figure 6 is a vertical sectional view on the line 6-6 of Figure 10,showing the position of the valve lifters when the control handle ispositioned for medium pressure operation and wherein but one of thecontrol valves is open;

Figure 7 is a horizontal sectional View on the line '7 7 of Figure 6,wherein the arrows indicate the directional ow of the pressure lluid inthe valve rblock during'the pressure stroke and only one of the controlvalves is open, as when the control handle is positioned for mef diumpressure operation; Y

Figure 8 is a vertical sectional view similar to 'Figure 6, but showingthe valve litters positioned for low pres-v sure operation, and whereinthe two controlv valves are closed;

Figure 9 is a horizontal sectional view on the line 9-9 of Figure 8,wherein the arrows indicate the directional iiow of the pressure tluidin the valve block during the pressure stroke and the two control valvesare closed, as when the control handle is positioned for low pressurehigh volume operation;

Figure lOis a vertical sectional view substantially on the line 10-10 ofFigure 2, showing the position of the valve lifter, when the controlhandle is positioned for medium pressure operation, as in Figure 6; and

Figure l1 is a vertical sectional view similar to Figure 6, `showing thevalve lifter positioned for high pressure operation, wherein the twocontrol valves are open.

Housing and pump operating means The novel hydraulic pump hereindisclosed is shown embodying a housing, generally designated by thenumeral Z, comprising front and rear walls 3 and 4, respectively, sidewalls 5 and 6, and a bottom wall 7. The upper end of the housing isnormally closed by a cover plate 8 securedv to the upper portions of theupright walls of the housing by suitable cap screws or bolts 9,indicated in Figures 1, 2 and 3. The cover plate 8, upright walls 3, 4,5 and 6, and the bottom wall 7,V cooperate to provide a closed reservoirfor the pressure fluid, indicated at 10a in Figures 1 and 2.

The cover plate 8 is shown providedwith an upward extension 11 which maybe integral therewith. The uppermost end of extension 11 is slotted asindicated at 12 in Figure 1 to receive one end of an operating lever 13,pivoted to extension 11 by a suitable pivot pin 14. The operating lever13 is shown provided with a cylindrical grip portion 15 adapted to begrasped by a hand of the operator.

VPump cylinder and piston assembly An important feature of the presentinvention resides in the novel construction of the pump means providedwithin the` housing and reservoir for pumping the fluid therefrom at theselected volume and pressure. The pump means comprises acylinder-forming member, generally designated by the numeral 16, havingits upper end portion ixedly secured to the cover plate 8 by suitablemeans such asrbolts 17. To prevent the formation of a vacuum within thehousing above thelevel of the iluid, a suitable vent, not shown in thedrawings, may be provided in the cover plate 8 to permitfree-circulation of atmospheric air into and out of the housing duringoperation .of the pump. In actual operation ofthek pump, it has beenfound that by not utilizing a gasket between the cover plate 8 and itsseat at the upper end of the housing, adequate air circulation into andout of the housing may readily be pro# vided for, as will be understood;

.Cylinder member 16 has an enlarged bore 18 at its upper end whichterminates at its lower end in a reduced bore 19. Bore 19 extends to4the bottom of member 16, as shown in the drawings. To facilitateexplanation, bores 18 and l19 will hereinafter be referred to as the lowand medium pressure cylinders, respectively. Cylinder member 16 also hasa vertical fluid circulating passage 20 therein, the upper end of whichis in direct communication with the bottom of cylinder 18. See Figures4, 6, 8 and 11. Fluid circulating passage 20 is laterally olf-set fromthe aligned axes of cylinders 18 and 19. g Passage 20 serves to conductthe pressure fluid from reservoir 10 to cylinder 18 during the suctionstroke of the pump, as indicated by the arrows in Figure 4. Under otheroperating conditions of the pump, fluid circulation through passage 20is reversed, as will subsequently be described.

- i A valve block, generally designated by the numeral 21, subsequentlyto be described, is secured to the lower end of member 1 6 by suitablemeans such as cap screws or bolts, indicated at 21a inl Figures 5, 7 and9. Valve block 21 provides a closure for the lower end of Ithe reducedbore or cylinder 19.

An enlarged piston 22 is mounted for reciprocalmovement in cylinder 18and has the lower end of a piston rod 23 secured to its upper end. Theupper end of piston rod 23 is pivoted to the lower end of a connectinglink 24 by a pivot pin 25. The upper end of connecting link 24 ispivotally connected to the operating lever 13, as indicated at 25a inFigure 1. v

A relatively smaller hollow piston 26 has its upper end secured topiston 22 and extends downwardly therefrom into cylinder 19 in which ithas the usuall piston-like t, as will be understood by reference toFigures 4, 6, v8, 10 and 11 ofthe drawings. l

Piston 26 has a relatively smaller bore 27 therein which willhereinafter be referred to as the high pressure cylinder. rIthe upperend portion of a relatively smaller fixed piston 28 is slidably receivedin cylinder 27. PistonZS has its lower end xedly secured -to the Valveblock 21 by such means as screw threads, indicated at 29 in thedrawkings. See Figures 6 and 11. e The above described parts thuscooperate to provide a plurality of piston and cylinder assemblies, inthis particular instance three, all of which are axially aligned andnested, one within the other. This constitutes an irnportant feature ofthe invention in that it greatly facilitates the operation of machiningthe parts. Moreover, it results in a relatively lower and more compactand light weight unit. The enlarged cylinder 18 and piston 22 cooperateto provide the low pressure, high volume pump; piston 26 and cylinder 19cooperate to provide the medium pressure, medium volume pump; and thefixed piston 28 and movable cylinder 27 cooperate to provide the highpressure, low volume pump.

The pressure control mechanism, subsequently to be described,selectively controls the output of the three pumps. VIt is soconstructed that when positioned for low pressure high volume flow, theiluid simultaneously drawn into the three pumps during the suctionstroke is directed into the delivery tube, from whence it ows to theservice line. When the control mechanism is positioned for mediumpressure medium volume flow the fluid in low pressure cylinder 18 isreturned uninterruptedly to the reservoir whereas-only the uid fromcylinders 19 and 27 is directed into the delivery tube` for subsequentdelivery into the service line. This results becauserof control valve S3being retained in open position by valve lifter 101, as

shown in Figure 6.

In like manner, when the control mechanism is positioned for highpressure low volume operation the uid contained inl the two relativelylarger low and medium pressure cylinders 18 and 19 is returned directlyto the reservoir during the pressure stroke, as indicated by the arrowsin Figure l1, and only the fluid in the high pressurel cylinder 27 isdirected into the delivery tube for subsequentdelivery to the serviceline. Thus, fluid is circulated freely through all pumps during eachcycle of operation but only that portion of the uid delivered into thedelivery tube is utilized for effecting the work operation.

Mounted within the upper end portion of the intermediate pressure piston26 is a check valve, generally designated by the numeral 31. This valvecontrols the delivery of pressure uid into high pressure cylinder 27,and hasa valve head 32 adapted to engage a valve seat 33 provided at thelower end of a valve cage 34. Valve cage 34 is xedly mounted in a bore35 in the upper end portionof cylinder 26, and is shown secured thereinby the threaded extension 36 of the piston rod 23, as will be understoodby reference to Figure 6. A suitable lock screw 37 may be mounted Vinthe enlarged piston 22 for locking said piston to the threaded extension36 of piston rod 23, whereby it is not likely to become detachedtherefrom. A brass plug 38 is shown interposed between the inner end oflock screw 37 and the periphery of the threaded end portion 3b of member23, thereby to prevent damage to the threads thereof, as is well knownin the art.

The valve cage 34 is shown provided with transverse fluid passages 39which register with similar uid passages 41 in the upper end portion ofpiston 26. A suitable spring 42 is secured to the upper end of checkvalve 32 and constantly tends to urge it upwardly into engagement withits seat 33, as will be understood by reference to the drawings.

Valve mechanism Another important feature of the present inventionresides in the unique construction of the valve mechanism forcontrolling the directional flow of the pressure uid during operation ofthe pump. The valve mechanism is best illustrated in Figures 4 to 11,inclusive, and comprises the valve block 21, in which all the valves ofthe pump are contained, with the exception of the check valve 32 mountedin the upper end of piston 26.

Within the valve block 21 are two horizontal uid passages 43 and 44,shown spaced laterally from one another;

, fand having their rear ends closed by suitable plugs 45, received inthreaded sockets provided in the valve block, as clearly illustrated inFigures 5, 7 and 9, Plugs 46 and 47 are secured in threaded socketsprovided in the bottom face of the valve block 21 with their axesintersecting the axes of their complemental iiuid circulating passages43 and 44, as will be understood by reference to Figures 5, S and 9.Plugs 46 and 47 are each provided with fluid circulating passages 43 and49, respectively, adapted to establish communication between thereservoir 1i? and the horizontal fluid circulating 'passages 43 and dduring operation of the pump, as will subsequently be described.

Axially aligned with the fluid passages 48 and 49 in the plugs 46 and 47are valve chambers 51 and 52. Control valves 53 and 54 are contained invalve chambers 51 and 52, respectively, and are adapted to engage valveseats 55 and 56 provided respectively at the upper ends of plugs 46 and47, as will be understood by reference to Figures 6, 8 and ll, therebyto control fluid flow through Valve passages 4S and 49, to and from thehorizontal fluid circulating passages 43 and 44.

The opposite or front ends of fluid circulating passages 43 and 44 areconnected to a pair of valve chambers 57 and 58 respectively, havingvalve seats 59 and 61 adapted to be engaged by spring pressed checkvalves 62 and 63, respectively. Springs 64 constantly urge valves 62 and63 into seating engagement with their respective seats 59 and 61, aswill be understood by reference to Figures 5, 7 and 9. Valve chambers 57and 58 are partially formed in the valve block 21 and by thecounterbores provided in the inner ends of plugs 65 and 66. The innerends of plugs 65 and 66 terminate short of the bottoms of the valvechambers 57 and 58, thereby to provide uid circulating passages betweensaid valve chambers and a connecung fluid circulating passage 67, asclearly illustrated in Figures 5, 7 and 9, whereby the pressure fluidmay ow from the horizontal passages 43 and 44 into the connectingpassage 67 under certain operating conditionsvof the v pump.

It is to be understood that the upright fluid circulating passage 20 inthe cylinder member 16 provides free uninterrupted fluid circulationbetween the low pressure cylin- Ader and the horizontal fluidcirculating passage 43, and

in like manner, the lower end of the medium pressure cylinder 19 isconstantly in direct communication with the horizontal fluid circulatingpassage 44 through an upright passage 68, shown in Figures 4, 5, 6and-8.

Mounted in the valve block 21 in axial alignment with the fixed piston28 is a valve cage 69 which contains a spring pressed check valve 71which normally closes the lower end of a high pressure fluid passage 72extending lengthwise through the fixed high pressure piston 28. Theinterior of the valve cage 69 is in direct communication with a uidcirculating passage 73 having one end in direct communication with ltheconnecting passage 67, as best indicated in Figure 5.

A delivery tube, generally designated by the numeral 74, has one endconnected directly to the connecting passage 67 shown in Figures 5, 7and 9, by a suitable fitting 75. The opposite end of tube 74 isconnected to a pressure relief valve 76, best shown in Figure l. A tube77 has one end attached to the relief valve 76 and extends upwardlytherefrom through an aperture in the cover plate 8, as will beunderstood by reference to Figure l. The upper end portion of tube 77 isthreaded as shown to receive clamping nuts 78 for securing the tube inthe cover plate 8. The projecting end portion 79 of the tube 77 providesmeans for attaching one end of a suitable service conduit to the pump,as is well known in the art.

Control means, valve lifters, etc.

Another important feature of the present invention resides in the novelmeans whereby the pump may be quickly shifted from one operatingcondition to another by the simple manipulation of a single controlhandle or element. This control is generally designatedv by the numeralS1, and is shown mounted on a pivot 32 secured to the upward extension11 of the cover plate 8.

he control handle 81 has an enlarged head 83, the periphery of which iseccentric to the axis of the head 83, as clearly illustrated in Figure2. ".l`lne periphery of the head 83 comprises a plurality of cam faces84, 85, and 36, each adapted to be engaged by the upper end of a valvelifting rod S7 having its upper end slidably mounted in a guide 8Sforming a part of the cover plate 8. An abutment shoulder 39 may beprovided on the periphery of the head 83 of the control handle 81adjacent to cam face 84 to limit the rotary movement of the controlhandle in one direction, as will be understood by reference to Figure 2.The lower end portion 70 of rod 37 is threaded, as best illustrated inFigure 4, and is loosely or floatingiy received in an aperture 80,provided in a cross head 91. Lock nuts are received in threadedengagement with rod S7 and provide means for vertically adjusting theupper end of rod 87 relative to cam face S4, when the `control handle 81is in its high pressure low volume position I-I, shown in full lines inFigure 2.

The cross head 91 extends inwardly from the rod S7 in a directiontowards the valve block 21, as best illustrated in Figure l0, and hasadjustably secured to its inner marginal edge portion a pair of uprightguide rods or bolts 93 and 94. The lower ends of guide bolts 93 and 94are received in threaded engagement with the cross head 91, as indicatedin Figure 4, whereby they are adapted for relative vertical adjustmenttherein. Suitable lock nuts 95 are secured in threaded engagement withthe lower terminals of bolts 93 and 94 whereby they may be securelylocked in adjusted position in the cross head.

Guide bolts or rods 93 and 94 extend upwardly through suitable guideopenings 96, indicated in dot-ted lines in Figures 2 and l0 of thedrawings. Coiled about the upper projecting end portions `of the guiderods 93 and 94, above the valve block 21, are a pair of coiled springs97. These springs have their lower ends seated on the top surface ofvalve block 21, and their upper ends are shown engaged with washers 98seated against the heads 99 of the two guide bolts, as clearlyillustrated in Figure l0.

Valve lifter rods or screws 101 and 1112 are received in threadedengagement with the cross head 91 and are adapted for independentvertical adjustment therein to assure seating of the control valves 53and 54, as shown in Figure 8 of the drawings, when the control handle 81is in its low pressure high Volume position L shown in full lines inFigure 2. Lock nuts 103 fixedly secure the valve lifter rods 161 and 102in their adjusted positions in the cross head 91, whereby they are notlikely to relatively shift their positions therein when the pump is inoperation. The upwardly extending end portions of the valve lifterScrews 101 and 102 are freely movable longitudinally in the enlargediiuid circulating passages 48 and i9 of control valves 53 and 54,respectively.

When the control handle 81 is in its low pressure high volume position L(see Figure 2), the upper terminals of valve lifter screws 1111 and 1132are in their retracted positions out of direct contact with theirrespective control valves 53 and 54, as best illustrated in Figure 8,whereby said valves engage their respective seats at the upper ends ofvalve bushings 46 and 47 and thus prevent the fluid in cylinders 18 and19 from returning directly to the reservoir 10 via uid passages 48 and49.

To assure proper operation of the pump, the valve lifter mechanism mustbe so arranged and adjusted with respect to the control handle 81 thatwhen said handle is in its low pressure high volume position L, thevalve lifter pins 101 and 102; are out of direct contact with theirrespective control valves 53 and 54, as shown in Figure 8, whereby saidvalves engage their seats and prevent return flow of the pressure fluidfrom their respective cylinders 18 and 19 to the reservoir.

By reference to Figure 8 it will be noted that the valve lifter pins areso positioned in the cross head 91 that the upper end of valve lifterpin 101 is spaced downwardly from its closed control valve 53 justenough to permit said valve to close. The upper terminal of' valvelifter pin 102, however, is spaced a substantial distance from itscontrol valve 54 for reasons subsequently to be described. Y

When kthe control handle 81 is shifted from low to its medium pressureposition M, the relatively longer valve lifter pin 101 unseats controlvalve 53 to permit fluid flow from cylinder 1S to the reservoir throughpassage 48, as indicated by the arrows in Figure 6.- In

this position the control valve 54 remains closed because of valvelifter pin 1112 being relatively shorter than valve lifter pin 101. Whenthe control valves are positioned as shown in Figure 6, theiiuid in themedium and high pressure cylinders 19 and 27 is forced into connectingchannel 67, from whence it flows through the delivery f tube 74 Ito theservice line.

When the pump is to be operated at high pressure low volume ilow, thecontrol handle 81 is shifted to the full line position I-i, shown inFigure 2, whereupon the control valves 53 and 54 are unseated by thevalve lifter pins 101 and 102, as shown in Figure l1, thereby permittingthe pressure fluid in the low and medium pressure cylinders 18 and 19,respectively, to return uninterruptedly to the reservoir through theopen control valves S3 and 54, upon the pressure stroke of the operatinglever 1S, as indicated by the arrows in Figure ll.

When assembling the valve lifter mechanism in the pump assembly theguide rods or bolts 93 and 94 are inserted through the vertical guideopening 96 in the valve block 21, the springs 97 being iitted onto saidbolts before inserting them into the vertical guides 96. The lowerterminals of guide bolts 93 and 94 are received in threaded engagementwith cross head 91, as hereinbefore stated, and are verticallyadjustable therein to accurately space the cross head 91 from the valveblock and particularly from the plane a--a of the under faces of theheads 99 of guide bolts 93 and 94, as best indicated in Figure 4. It isof utmost importance to the operation of the valve lifter that the uppersurface of the cross head 91 is parallel to the plane a-a of bolt heads99. Before mounting the cross head`91 on the valve block the operatingrod 87 may be installed with its lower end 70 oatingly received in theaperture 80 in the cross head. =Lock nuts 90 on the lower end portion ofvalve lifter rod 87 retain said rod in its position in the cross head 91whereby its upper terminal is properly positioned with respect to thecam faces of the control handle 81.

The valve lifter pins or screws 191 and 102 may then be verticallyadjusted in the cross head and secured in fixed position therein by thelock screws 193, with their upper terminals so positioned withrespect toVthe valve seats of the two control valves 53 and 54 that the operationof said valves, as hereinbefore stated, is assured.

To facilitate accurately positioning the valve lifter rods 101 and 102in the cross head 91, when initially assembling the apparatus foroperation, valve chamber S1, for example, may be made relatively largerthan valve chamber 52 in a vertical direction, as best illustrated inFigures 4, 6 and 11. By a careful inspection of these figures it will benoted that the top wall 51 of valve chamber 51 is located at arelatively higher elevation Ithan the top wall 52' of valve chamber 52.The difference in elevations between the top walls 51 and 52 correspondsubstantially to the variations in the locations of the upper terminalsof valve lifter rods 101 and 192.

When initially assembling the valve lifter mechanism in valve block 21,the control handle 81 is preferably positioned for high pressure lowvolume ow, as shown Y at H in Figure 2. The lower end of valve lifterrod 81 is then inserted in the aperture 80 in the cross head 91 and thelock nuts 90 thereon manipulated to position the cross head 91 at afixed elevation relative to the valve seats 55 and 56.- The valve lifterrods are next vertically A Operation To initially condition the pump foroperation, a suitable inelastic pressure lluid is introduced into thereservoir 10 through the ll opening, indicated at 104, in Figure 3,after which the operating lever 1S is operated through several completestrokes to make sure that all lluid circulating passages, channels andcylinders are completely filled with uid, and to eliminate air pocketsfrom the fluid circulating system.

It is to be understood that before the cover plate S is secured inposition on top of the housing, the valve lifters 101 and 102 have beenchecked for proper positioning with respect to their control valves S3and 54 to make certain that when the control handle 81 is in its lowpressure, L position, indicated in dotted lines in Figure 2, the controlvalves S3 and 54 will be engaged with their respective seats 55 and S6,as shown in Figure 8. When so positioned, the tluid in cylinders 1S and19 cannot return directly to the reservoir through passages 48 and 49,during the pressure stroke of the operating lever 15, and is thendelivered into the cross channel 67 and into the delivery tube 74 toeffect low pressure high volume operation.

Low pressure-high volume Jiow When the pump is to be operated at lowpressure high volume ow, the control arm 81 is shifted to the dotted-line position L in Figure 2, whereby control valves 53 and 54 engagetheir respective seats and prevent the uid drawn into the low and mediumpressure cylinders 18 and 19 during each suction stroke (see Figure 4),from returning directly to the reservoir 11i through valve passages ditand 49, as will be understood by reference to Figure S, during thepressure stroke of operating lever 15.

AAssuming now that the operating lever 1S is in its lowered position, asshown in Figure 1, and the operator grasps lever 15 and pulls itupwardly. Such action will cause pistons 22 and 26 lto move upwardlysimultaneously in their respective cylinders 18 and 19, thereby causinga suction or vacuum to develop in said cylinders which unseats controlvalves 53 and 54 and permits pressure Huid to be drawn into cylinders 18and 19 through fluid passages 20 and 68, respectively, as indicated bythe arrows in Figure 4.

At the same time a vacuum is formed in the high pressure cylinder 27causing check valve 32 to open and permit pressure uid to enter cylinder27 through passages 39 and 41 from cylinder 13, as clearly indicated bythe arrows in Figure 4. During the suction stroke of the pump the highpressure check valve 71 at the bottom of passage 72 in the stationaryhigh pressure piston 28 is closed, as shown.

When the valve lifters are positioned for low pressure, as abovedescribed, the pressure uid contained in all of the cylinders is forcedtherefrom into the connecting passage 67 during each pressure stroke ofthe operating lever 15, as indicated by the arrows in Figure 9, fromwhence it is forced upwardly through the delivery tube 74 and pressurerelief valve 76 to the service line, not shown. Such directional flow ofthe pressure fluid from the various cylinders is brought about as aresult of the control valves 53 and 54 being closed, as shown in Figure8. p

Under such conditions the pressure of the duid in uidcirculatingpassages 43 and 44 is increased to lthe extent that the tension insprings 64 is overcome, whereupon check valves 62 and 63 open and permitthe iuid in the low and intermediate pressure cylinders 18 and `19,respectively, to enter the connecting channel 67, to which the deliverytube 74 is` directly connected. At the same time the high pressure checkvalve 71 is unseated from the lower end of the stationary high pressurepiston 28 to permit the pressure fluid in the high pressure cylinder 27to enter the connecting passage 67 from passage 73 (Figure for deliveryinto delivery tube 74, as indicated by Vthe arrows in Figure 9.

When the operating lever 15 is pulled upwardly by the operator, controlvalves 53 and 54 will open, as shown in Figure 4, and the pressure uidthen enters the horizontal fluid circulating passages 43 and 44 from thereservoir 10, through fluid passages 48 and 49, and thence ilowsupwardly through passage 20 into the low pressure cylinder 18.Simultaneously, fluid is drawn into the medium pressure cylinder 19through passage 68, as indicated by the arrow 50 in Figure 4. At thesame time a vacuum develops in the high pressure cylinder 27, whereuponcheck valve 32 at the upper end of the high pressure cylinder 27 isopened to permit the uid to enter said cylinder from the low pressurecylinder 18, as indicated by the arrows in Figure 4, therebyconditioning the pump for the next pressure stroke.

Medium pressure-medium volume flow To operate the pump at mediumpressure and medium volume flow, the control handle 81 is shifted intoits vertical or intermediate position, indicated at M in Figure 2,whereupon kthe valve lifting rod 87, the upper end of which is normallyretained in engagement with one of the cams 84, 85 or 86 of the controlhandle 81 by springs 97, moves upwardly into engagement with cam face 85of the control handle 81. Such relative upward movement of Valve lifterrod 87 elevates cross head 91 to the position shown in Figure 6, wherebyvalve lifter 101 engages and unseats control valve 53. When the controlvalve 53 is thus unseated, the pressure fluid in low pressure cylinder18 returns to the reservoir through passage 48 during the pressurestroke of the pump lever 15.

The suction stroke of the pump, when the latter is adjusted for mediumpressure operation, is the same as when the pump is adjusted for lowpressure operation. On the pressure stroke, however, the fiuid containedin the low pressure high volume cylinder l is permitted to ilow freelyfrom said cylinder through the vertical passage 20, horizontal passage43 and the open control valve 53 back into the reservoir. The fluiddrawn into the medium pressure cylinder 19 cannot return to thereservoir as a result of the control valve 54 being closed, as shown inFigure 6. Thus, the fluid contained in cylinder 19 is forced into theconnecting passage 67, as indicated by the arrows in Figure 7, andthence into the delivery tube 74. Simultaneously, the pressure huiddrawn into the high pressure cylinder 27 is forced therefrom throughcheck valve 71 into duct 73, and connecting passage 67, and thence intothe delivery tube. See Figure 7.

High pressure-low volume fi'ow For high pressure low volume operation,the control handle 81 is shifted to the full line position H in Figure2. When so positioned, the valve lifter rod 37 is elevated by thesprings 97 to the position shown in Figure 1l. In this figure it will benoted that the -upper terminals of valve lifters 101 and 102 havecompletely unseated the control valves 53 and 54, whereby the iiuid inthe low and medium pressure cylinders 18 and 19, respectively,

passages 48 and 49, as indicated by the arrows in Figure Y 10 Y 11,during the pressure stroke of the operating lever 15.

Because of the pressure fluid being thus permitted to freely escape fromthe low and medium pressure cylinders 18 and 19, the check valve 32 inthe upper portion of the high pressure cylinder 27 is closed by spring4Z, and as the pump lever 15 is. forced downwardly, the pressure of thefluid in cylinder 27 unseats check valve 71 at the bottom of the passage72 of the fixed piston 28, from whence the fluid enters the connectingpassage 67 through passage 73 and thence iows on through the deliverytube 74, relief valve 76, to the service line.

When the pump is not in use the control arm 81 may be in its lowpressure position, indicated at L in Figure 2, but not necessarily so.There may be times when the operator may deem it advisable to leave thecontrol handle S1 in its intermediate pressure position M, or in itshigh pressure position I-I. p

The pump is extremely simple and inexpensive in construction and ishighly efficient in operation. The unique arrangement of the variouscylinders and pistons greatly simplies construction in that the pistonsand cylinders may be completely assembled on the cover plate 8 beforemounting within the housing 2. In like manner the valve mechanism andvalve lifter may be completely assembled independently of the piston andcylinder assembly, whereby the various valves and working parts of thevalve lifter may be carefully inspected and adjusted before beingembodied in the composite pump. l

The valve lifter, including the rod 87, control arm 81, cross head 91,guide rods 93 and 94, and valve lifter rods or pins 101 and 102 may alsobe completely assembled on the cover plate and valve block before beingassembled in the housing 2,A as will readily be understood by referenceto the drawings, whereby all of said parts may readily and quickly beadjusted to accurately position the terminals of the uvalve lifters withrespect to their ball valves 53 and 54. In like manner the cross head 91may readily be operatively connected to the lower end of the lifting rodS17 to assure correct operation of the control Valves 53 and 54 for thevarious positions of the speed control handle 81.

The housing 2 is shown provided at its lower portion with oppositelydisposed leg elements 103 which are apertured to facilitate anchoringthe housing to a suitable support, either fixed or portable. If the pumpis to be utilized as a portable device the housing may be secured to asuitable piece of timber extending from at least the rear of the housingto a suitable distance forwardly of the housing, whereby the operatormay, if necessary, place a foot on the supporting member when operatingthe pump.

A suitable iller plug 104 is shown provided in the cover plate 3, and adrain plug 10S is provided at the lower portion of the housing, as bestshown in Figures l and 2.

Another important constructional feature of the pump herein disclosedresides in the unique arrangement of the various cylinders and pistonsin the single supporting member 16. All cylinders and pistons areaxially aligned with one another and are nested together to provide avery compact unit having a wide range of pressures. lThe variouscylinders and piston combinations are so interconnected that they areoperated simultaneously, when the operating lever 15 is manipulated. Thecomposite pump is always available for any desired pressure within itslimits by simply shifting the control handle 81 to the positionrepresenting the required pressure.

The pump has been found extremely practical and highly eicient when usedin combination with other equipment requiring the use of -a pressurefluid to accomplish certain work operations. For example, the pump asherein disclosed is adapted to operate under three different workingpressures, namely, 300 p.s.i., 500 p.s.i. or 10,000 p.s.i. Should thework to be accomplished require a working pressure of approximately10,000` pounds, the pump may be quickly brought up to full or maximum 11pressure because of the unique arrangement andconstruction of the lowand medium pressure pumps, by progressively shifting the control handleS1 from its low pressure position L, through medium pressure position M,and into its high pressure position H during operation of the pump. Whenthe control handle is so positioned, and the operating lever isactuated, the low and medium pressure cylinder and piston combinationswill operate to maintain a full supply of fluid for the high pressurecylinder 27 through check valve 32, as will be understood by referenceto Figure 4. In like manner, the pump may be quickly shifted from highpressure operation to a lower pressure operation without interruption.

The invention may be embodied in other specific forms without departingfrom the essential characteristics thereof. Hence, the presentembodiments are therefore to be considered in all respects merely asbeing illustrative and not as being restrictive, the scope of theinvention being indicated by the appended claims rather than by theforegoing description, and all modiiications and variations as fallwithin the meaning and purview and range of equivalency of the appendedclaims are therefore intended to be embraced therein.

I claim as my invention:

l. In a variable pressure hydraulic pump, a housing forming a reserv'oirhaving an inelastic pressure fluid therein, a cover plate secured to theupper end `of said housing and having an operating lever pivotedthereon, a cylinder-forming member secured to said cover plate andpositioned within the housing, said cylinder member comprising aplurality of axially aligned cylinders, a piston mounted in eachcylinder, means connecting said pistons to the operating lever wherebysaid pistons are adapted for simultaneous operation, a valve blocksecured to the lower end of said cylinder-forming member and having aplurality of fluid-circulating passages therein communicating with saidcylinders, a delivery tube connected to the valve block, check valves incertain of said uid circulating passages yfor controlling fluidcirculation therethrough, control valves in the valve block forcontrolling iluid ilow to and from said cylinders, a valve liftermechanism for actuating said control valves to vary the elfectivepressure and volumetric flow of the fluid delivered from the deliverytube, said valve lifter mechanism comprising spaced upright valveengaging elements having an operating member located exteriorly of thehousing whereby the operator may conveniently manipulate said controlmember to cause the pump to operate at any selected uid pressure andvolumetric ilow within the range of the pump.

2.. A hydraulic pump according to claim 1, wherein the valve lifterelements are adjustably supported in a common supporting member havingone end of an operating rod connected thereto, the opposite end portionof said rod projecting from the housing whereby it may readily andconveniently be actuated by the operator to shift the positions of thecontrol valves with respect to their seats, thereby to selectively varythe effective pressure of the tluid delivered from the pump.

3. A hydraulic pump according to claim 2, wherein means is mounted onthe cover plate for actuating said operating rod, said means comprisinga rotatably mounted member having a plurality of cam elements thereonadapted to engage said rod, said member also having an operating handlefor facilitating manual shifting of said rod.

4. A hydraulic pump according to claim 3, wherein the cover plate forthe housing, the cylinder-forming member, the valve lifter mechanism,and the operating lever may all be assembled as a composite workableunit prior to securing the cover plate in position on the housing,thereby to facilitate manufacture.

5. In a hydraulic pump of the class described, a housing having aninelastic fluid therein, a cover plate for 12v the housing, acylinder-forming member secured to the cover plate and depending intothe housing, said cylinderforming member comprising an enlarged low'pressure cylinder and a relatively smaller medium pressure cylinderaxially aligned with one another, pistons'l mounted in said cylindersand connected to a single operating member for simultaneous operation,the piston in said medium pressure cylinderrhaving an axial bore thereinforming a movable high pressure cylinder, said high pressure cylinderhaving a valved connection with said enlarged cylinder, a memberextending upwardly from the lower end of cylinder-forming member andproviding a xed piston for said movable high pressure cylinder, a valvemechanism at the `bottom of the cylinder-forming member having aplurality of fluid circulating passages therein, a delivery tube, checkvalves in said valve mechanism for establishing communication betweenthe reservoir and said fluid circulating passages during the suctionstroke of the pump, control valves also in said valve mechanism forcontrolling the volumetric ilow of the pressure uid delivered fromthepump and the effective pressure of said uid, and means exteriorly of thehousing for t actuating said control valves to cause the pump to deliveruid at any selected pressure and volume within its limits.

6. In a hydraulic pump of the class described, a housing having a fluidreservoir in the lower portion thereof, an inelastic iiuid in thereservoir, pump means mounted in the housing and comprising a pluralityof axially aligned cylinders of different diameters, a piston 'm eachcylinder, an operating lever for simultaneously actuating said pistons,Vvalve means for controlling the flow of pressure fluid to and from thecylinders from the reservoir during operation of the operating lever, adelivery tube having one end in communication with the valve means andhaving means at its opposite end for connecting it to a service line,said valve means including a pair of control valves normally tending tomove into closed positions, when the pump is at rest, a valve lifteroperable to successively unseat said control valves from theirrespective seats to control the effective output of the pump, said valveunseating means comprising a vertically movable cross head having a pairof spaced upright valve engaging elements mounted therein, one for eachcont-rol valve, and means operable from the exterior of the housing formanually actuating said valve lifter to unseat the control valves andthereby vary the operation of the pump.

7. A hydraulic pump according to claim 6, wherein a cam member ismounted on the upper end portion of the pump within convenient reach ofthe operator, said cam member comprising a plurality of cam elementsadapted to engage the upper en'd of the valve lifter control rod,thereby to vertically translate the valve lifter elements in accordanceto the pressure at which the pump is to be operated.

S. In a pump of the class described, a housing having a reservoirtherein, an inelastic -tluid in the reservoir, a cover plate secured tothe upper end of the housing, a cylinder-forming member secured to thecover plate and having its lower end portion extending into the fluid inthev reservoir, said cylinder-forming member comprising an enlarged lowpressure high volume flow cylinder and a relatively smaller mediumpressure medium volume ow cylinder axially aligned with said lowpressure cylinder, a valve block secured to the lower end of saidcylinder-forming member and having a plurality of fluid circulatingpassages therein, check valves and control valves in said uidcirculating passages for controlling the flow of fluid to and from thecylinders from the reservoir, during operation of the pump, a deliverytube for conducting the pressure iiuid from the pump to a service line,said medium pressure piston having an axial bore therein forming a highpressure cylinder, a tubular member extending upwardly from the valveblock and having its upper end slidably received in the bore in saidmedium pressure piston and forming a stationary high pressure piston,said high pressure piston having an axial fluid passage therein forestablishing communication between the high pressure cylinder and thefluid circulating passages in the valve block, a check valve in theupper portion of said medium pressure piston for establishingcommunication between the low and high pressure cylinders, and anoperating lever connected to said low and medium pressure pistonswhereby said low, medium, and high pressure cylinder and pistoncombinations are actuated simultaneously to cause the pump to deliverpressure fluid from its delivery tube at a selected pressure andvolumetric flows determined by the manual positioning of the controlvalves by the operator.

9. A hydraulic pump according to claim 8, wherein the valve blockcomprises av pair of horizontally disposed spaced parallel fluidcirculating passages, a cross channel for establishing communicationbetween the corresponding ends of said uid circulating passages, springbiased check valves normally closing the connection between said uidcirculating passages and the cross channel, control valves in said valveblock for establishing communication between the reservoir and saidhorizontal iluid circulating passages, a delivery tube having one end incommunication with the cross channel and its opposite end projectingfrom the housing and adapted to be connected to the service line, and avalve lifter for actuating the control valves, thereby to selectivelycontrol the effective pressure and volumetric flow of the fluiddelivered by the pump.

10. A pump according to claim 9, wherein a fluid circulating ductconnects the lower end of the axial iluid passage in the xed highpressure piston to said cross channel, and a normally closed check valvein the valve block for controlling the flow of high pressure fluid fromthev high pressure cylinder to said cross channel at low volume, whenthe control valves are unseated by the operator, thereby to cause theuid in the high pressure cylinder to enter the cross channel anddelivery tube.

11. In a pump of the class described, a housing having an inelasticfluid therein, a pump body, a plurality of iluid circulating pumps insaid body each comprising a cylinder and piston, all of said cylindersand pistons being axially aligned with one another and nested togetherto provide a compact unitary structure, an operating member at the upperend of the housing for simultaneously actuating all of said pumps, avalve body secured to the lower end of the pump body and havinglaterally spaced horizontal fluid circulating passages therein, achannel for establishing communication between the corresponding ends ofsaid fluid circulating passages, check valves in said uid circulatingpassages for permitting one way flow of the fluid from said passagesinto said connecting passage, said connecting passage having one end ofa delivery tube in communication therewith the opposite end of which isadapted to be connected to a service line exteriorly of the pumphousing, a control valve in each yfluid circulating passage forcontrolling fluid llow from the reservoir thereinto when the pumps areoperated, means for manually successively unseating said control valvesto control the ow of iluid from the reservoir into said horizontal uidcirculating passages, said valve unseating means being manually operableto selectively control the unseating of said-control valves to cause thecomposite pump, when operated, to deliver pressure luid to the serviceline at a selected effective pressure and volumetric ilow, dependingupon the positioning of the control valves by said valve unseatingmeans, said valve unseating means comprising spaced parallel uprightvalve lifter elements, one for each control valve, a supporting memberfor said valve lifter elements, spring biased guide rods adjustablysecured in said supporting member and slidably received in guides insaid valve body, an operating rod for the valve lifter having its lowerend floatingly engaged with said supporting member, and means at theupper end of said rod for vertically translating it to shift thepositions of the valve lifter pins and thereby raise or lower thecontrol valves relative to their seats, thereby to vary the effectivepressure and volumetric flow of the fluid delivered by the pump.

References Sited in the file of this patent UNITED STATES PATENTS468,104 Weeks Feb. 2, 1892 833,457 Hammond Oct. 16, 1906 867,932 WeekslOct. 8, 1907 947,613 Gathmann Jan. 25, 1910 1,080,062 `'Hess Dec. 2,1913 2,044,857 Pfauser June 23, 1936 2,311,468 Pfauser lFeb. 16, 19432,442,058 Page May 25, 1948

